Gas-turbine (GT) engines operate to produce mechanical work or thrust. Specifically, land-based GT engines typically have a generator coupled thereto for the purposes of generating electricity. The shaft of the GT engine is coupled to the generator. Mechanical energy of the shaft is used to drive a generator to supply electricity to at least a power grid. The generator is in communication with one or more elements of a power grid through a main breaker. When the main breaker is closed, electrical current can flow from the generator to the power grid when there is a demand for the electricity. The drawing of electrical current from the generator causes a load to be applied to the gas turbine. This load is essentially a resistance applied to the generator that the gas turbine must overcome to maintain an electrical output of the generator.
Increasingly, a control system is used to regulate the operation of the GT engine. In operation, the control system receives a plurality of indications that communicate the current operating conditions of the GT engine including pressures, temperatures, fuel flow rates, and engine frequencies. In response, the control system makes adjustments to the inputs of the GT engine (e.g., changing fuel-flow splits), thereby changing performance of the GT engine based on the plurality of indications in light of look-up tables coded into the memory of the control system.
Over time, this performance may fall outside a preferred operating range due to mechanical degradation of the gas turbine engine or changes in operational conditions such as ambient temperature or inlet fuel properties (e.g., temperature, pressure, and composition). For instance, the gas turbine engine may begin operating in a state where combustion of the inlet fuel causes unwanted operational dynamics, such as instability or diminished durability. By way of example, total flow of the inlet fuel may have decreased/increased to cause a greater number of flashback events.
Within the field of technology pertaining to GT engines, there exists an undesirable condition called flashback. As used herein, “flashback” refers to an increase in the flame speed within the GT engine's combustor such that it causes the flame to move toward a premixer (i.e., location in which the air and gas are mixed). Traditionally, the onset of flashback is detected using thermocouples. However, the practice of employing thermocouples to monitor flashback results in imprecise readings and leads to cost disadvantages involved in purchasing and maintaining this expensive signal-measurement equipment.